The artificial rendering of an environment as seen by different types of sensors typically requires the implementation of dozens of types of special effects that, if not present, subvert the validity, and thus the value of the simulation. In order to portray a realistic simulated environment, the visual system used in connection with a simulation will need to possess the ability to generate effects such as: surfaces illuminated by the sun or moon depending on their position, the effects of various weather conditions, and illuminated colored surfaces representative of the temperature of ambient illumination present.
Concurrently, the electro-optical system of an effective simulation should be able to present features including: sensor gain representative of current scene illumination; gain related noise levels representative of the current scene illumination level; the reflective properties of materials with respect to the appropriate frequencies of light; proper panchromatic interpretation of visual colors; sensor exposure latitude limitations; illuminated surfaces affected by the position of the moon and other luminous objects; and lens flaring and light point haloing based off of the physical properties and emittance of the luminous object.
Often times certain simulations require an infrared system in order to portray a realistic environment. In order to be effective, such infrared systems should be able to present features including: proper panchromatic interpretation of visual colors (near-IR); proper representation of thermal properties of scene objects (far-IR); appropriate emittance properties for materials used in the database; heating and cooling related thermal properties; and sensor blooming representative of exposure latitude limitations of the sensor. In addition, simulated radar systems, both synthetic aperture and real-time, should be adapted to present: proper reflectance and absorption characteristics for all materials in the database; proper emitter source occulting and entity shadowing; and entity orientation based reflectance variations.
General effects require only simple mathematical calculations to accomplish. For example, illuminated surfaces that must emit without the need to cast light on non-luminant surfaces can be calculated similarly to simple surfaces possessing only reflective properties. Similarly, sensor gain effects need only average the scene illumination detected by the sensor being simulated and adjust the scene luminosity gamut accordingly. More dynamic effects however require more involved physics computations. For example, proper rendering of typical point light sources in visual and electro-optical simulations will require light halos, light blooming, scene gaining, point streaking, blockage near IR objects, reflections and light cast on non-emissive sources, to name a few.
The implementation of all requisite effects on all applicable objects in a simulation database naturally requires considerable amounts of computational time. With this in mind, many tactical real-time simulations can require the scene to be redrawn a minimum of sixty times each second, the minimal accepted rate considered to be imperceptible to most humans. Given the current state of graphics technology, or even that projected for the near future, those requisites cannot be met by the existing state of the art given the computational time required to calculate and render the physical properties of required effects for a minimal acceptable level of entities in a particular scene. FIG. 1 hereof is a flow diagram of one prior art method of generating a light map for an out the window display.
The success of a simulated training environment relies upon the simulation to immerse the trainee to the extent that they believe they're within the established environment. The most immersive effects however tend to also be the most prohibitively expensive, and thus computationally speaking, they are typically omitted from various simulations. This greatly limits the effectiveness of the immersive properties of a simulation, particularly at night.
There is thus a continuing need to improve the quality of optical effects so as to enhance the effectiveness of a given simulation.
It would also be desirable to shorten turnaround time in creating light maps to reduce delays in being able to implement a training program or practice an exercise. Typically, manually placing all the light points, adjustments, and other enhancements takes approximately three months.